Photographic developer.



UNITED STATES PATENT OFFICE.

BERT L. WILLIAMS, OF LOWVELL, MASSACHUSETTS, ASSIGNOR OF ONE- HALF TOFRED ALSON BRYANT, OF LOWELL, MASSACHUSETTS.

PHOTOGRAPHIC DEVELOPER.

Specification of Letters Patent.

Application filed September 6, 1904:. Serial No. 223,414.

To all whmn it may concern.-

Be it knownz'thatil, BERT L. VVILLIAMS, a citizen of the United States,residin in Lowell, in the county of Middlesex and ommonwealth ofMassachusetts, have invented a certain new and useful Improvement inPhotographic Developers, of which the following is a specification.

This invention relates to photographic developers of that variety whichare adapted for so-calledfi gas-light development papers, or papersdesigned to be exposed to artificial light or to diffused daylight andnot to the direct rays of the sun.

The developer herein described is not suitable for films, plates,(except lantern-slide plates or other diapositives,) or for bromidpapers.

The objects of this invention are to produce a developer which will notpoison the hands which will keep indefinitely before use withoutoxidation and for a very long time, almost indefinitely, after use;which will require only about half the usual time of exposure; whichwill secure purity of high lights and half-tones, perfect blacks, anduniformity of tone; which will correct the greenish-brown effect of anexcess-of bromid of potassium in thedeveloper, and which will insure anabsolute freedom from the frictionmarks or abrasionunarks on glossypaper. I accomplish these results by introducing into any developer ofthe amidophenol group for as-light papers about three grains of a souble salt consisting of iodin combined with a base to an ounce of normaldeveloper, using, preferably, iodid of potassium, by normal developermeaning developer of usual strength as used. Of course the concentrateddeveloper will require a proportionately larger amount of the salt ofiodin.

I have obtained entirely satisfactory results by using a developer ofthe followingnamed ingredients in the proportions stated below: to fiftyounces of water add successively thirty-five grains of metol, onehundred and fifty rains of hydroquinone, one hundred and fifty grains ofiodid of potassium, five hundred and fifty grains of dry sulfite of sodatwelve hundred grains of dry carbonate of soda, and five grains ofbromid of potassium. Still better, to clear thehigh lights andhalf-tones of the print, I may add (but do not consider it essential) tothe foregoing ten drops of the following solution, namely: water, eightounces; bromid of ammonium, one ounce; and bichromate of potash,one'ounce.

All of the above-named ingredients, except the iodid of potassium, havebeen com bined and used in substantially the proportions named fordeveloping photo raphic papers of thezclass first above specific Withthis developer as heretofore used (without the iodin salt) the leastvariation in the exposure or in the age of the developer is likely tocause dirty brownish tones, and an excess of bromid of potassium in thedeveloper will give a greenish-brown effect.

I have discovered that the addition of the soluble iodin salt in thedeveloper corrects.

all the troubles hereinbefore mentioned and implied, produces a fineclear tone, a perfect black, clear high lights and half-tones, and thata considerable variation in the proportion of bromid of potassium doesnot affect the tone of the print.

The developer containing the iodid can be used repeatedly untilexhausted and may be renewed as to uantity by adding new developer tothe o d without affecting the tone of the print. The use of thisdeveloper reduces the time necessary for exposure by one-half anddevelops glossy papers without abrasion-marks, sometlmes calledfrictionmarks.

Heretofore the only means of preventing abrasion-marks has been the usein the developer of hyposulfite of soda or cyanid of otassium, both ofwhich render necessary a onger exposure and injure the tone of theprint. The cyanid of potassium is also a deadly poison.

I do not intend to confine myself to the formula for ametol-hydroquinone developer above given, because the addition of asoluble iodid in about the proportion of three grains to the fluid ounceof normal developer to any of the developers used for gas-lightdevelopment papers and diapositives will produce the beneficial resultsabove described.

I claim as my invention 1. A photographic developer, including anamidophenol developing agent, and a soluble iodid, substantially asspecified.

2. A photographic developer, including an iodid, bichromate of potash,and bromid of lo amidophenol developing agent, and iodid of ammonium,substantially as specified. potassium substantially as specified. Intestimony whereof I-have aflixed my 3. A photographic developer,including an signature in presence of two Witnesses.

amidophenol developing agent, a soluble iodid, and bichromate of potash,substam" BERT WILLIAMS tially as specified. Witnesses:

ALBERT M. MOORE, GRACE CROWLEY.

4. A photographic developer, including an amidophenol developing agent,a soluble

